Английская Википедия:Cueros de Purulla

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Cueros de Purulla is a volcano in Argentina. It consists of a lava dome and an associated ignimbrite. A large eruption dated to c. 7820 BP deposited ash into the Valles Calchaquies.

Geography and geomorphology

The volcano lies in Catamarca Province of ArgentinaШаблон:Sfn Шаблон:Convert southeast of Antofagasta de la Sierra. Cerro Blanco volcano lies Шаблон:Convert south of Cueros de Purulla.Шаблон:Sfn

It is the northern of two lava domes which lie at the southern end of the Sierra de Calalaste and on its eastern flank.Шаблон:Sfn A Шаблон:Convert wide horseshoe-shaped collapse scar dominates the edifice of the lava dome and has generated large debris block.Шаблон:Sfn and hummocky debris.Шаблон:Sfn A second edifice developed within the collapse scar.Шаблон:Sfn The total volume of the volcano is about Шаблон:Convert.Шаблон:Sfn

The volcano is accompanied by ignimbritesШаблон:Sfn and a debris deposit consisting of obsidian lies at the foot of the dome. Two volcanic fallout units are associated with Cueros de Purulla. A lower fallout unit consisting of lapilli and volcanic ash extends several kilometres from the volcano, and remnants occur as far as Шаблон:Convert from it.Шаблон:Sfn The upper unit is formed by ignimbrites and pyroclastic density current deposits.Шаблон:Sfn

The volcano is part of the Southern Puna high plateau, where during the Neogene-Quaternary volcanism associated with the Andean Central Volcanic Zone produced both calderas and monogenetic volcanoes.Шаблон:Sfn The basement under Cueros de Purulla consists of Ordovician sediments, which are metamorphosed and intruded by volcanic rocks. This basement during the Permian was covered by continental sediments, and later during the Miocene to Holocene by volcanic rocks.Шаблон:Sfn

Composition and ores

Volcanic rocks erupted at Cueros de Purulla are rhyolites that define a potassium-rich calc-alkaline suite.Шаблон:Sfn Mineralogically, the rocks contain allanite, amphibole, apatite, biotite, clinopyroxene, epidote, feldspar, ilmenite, magnetite, muscovite, quartz, titanite and zircon.Шаблон:Sfn The volcanic rocks have been subdivided into three separate units, depending on whether they formed before the collapse or after it took place.Шаблон:Sfn

For the past five millennia,Шаблон:Sfn the volcano has been used as a source of obsidian, which occurs at Шаблон:Convert in the form of blocks and nodules of various colours, and is of high quality. Reportedly, gold and silver can be found at the volcano.

Eruption history

The lava dome at Cueros de Purulla is 400,000 ± 100,000 years old and produced volcanic units that resemble the older volcanics of Cerro Blanco; some were originally attributed to that volcano.Шаблон:Sfn At first, "coulee" lava flows were erupted and a large lava dome grew. After the collapse, the same processes rebuild part of the volcano. Notably, there is no indication that Cueros de Purulla produced block-and-ash flows.Шаблон:Sfn Based on the stratigraphic relations with volcanic rocks from Cerro Blanco, Cueros de Purulla was active during the last 73,000 years.Шаблон:Sfn

The "El Paso ash" in the Tafí valley was emplaced between 11802 and 4289 years before present and may originate at Cueros de Purulla volcano. A large eruption occurred during the Holocene, 7820 years before present (i.e. about 5870 BC). Deposits from this eruption form the Cerro Paranilla Ash in the Calchaquí Valleys, while a correlation to the 12,000-4,300 years before presentШаблон:Sfn so-called "VO ash" is unlikely.Шаблон:Sfn The eruption was highly explosive, forming a buoyant cloudШаблон:Sfn and depositing tephra as far as Cafayate in the Salta Province.Шаблон:Sfn

See also

• Cerro Torta

References

Sources

• Шаблон:Cite journal
• Шаблон:Cite journal
• Шаблон:Cite journal
• Шаблон:Cite journal